Rail flaw detector mechanism



Aug. 4, 1936. H DRAKE 2,049,764

RAIL FLAW DETECTOR MECHANISM Filed March 23, 1935 5 i 19 o o i o e o o oo R F II 12 2/ 20 30 31 1) r 7 Q I 4 24 I v 34$ 4, I 25 25 ZhwentorHarcourt C. Make 88 1 W I (Ittorneg Patented Aug. 4, 1936 STATES.

PATENT v 2,049,764 RAIL FLAW DETECTOR MECHANISM poration of New YorkApplication March as, 1935, Serial Natale 11 Claims.

This invention relates to rail flaw detector mechanisms and moreparticularly to the type of mechanism employed on the Sperry rail flawdetector cars. These cars operate on the fundamental principle ofsending current of high amperage through the rail to establish anelectromagnetic field and then exploring said field for irregularitiescaused by the presence of flaws within the rail. The exploring ordetector means comprises one or more sets of inductive means arrangedintandem along the rail. It was discovered that if coils extendingsubstantially across the railhead were employed, centrally locatedfissures were sometimesmissed because the diminution of flux at onepoint was counterbalanced by the increase in fiux at other points acrossthe rail head and a coil extending substantially across the rail headintegrated the flux so that apparently there was no diiferent total fluxat a place of fiaw than at a'region without flaw.

, In order to obviate this objection a plurality of sets of coils wereemployed, each set coacting with only a portion of the rail head widthso that one set of coils detected fissures nearer the gauge side while.thefother set detected fissures nearer the outside"of"the-rail head.The coils of each set are balanced-and in opposition, and the coils ofone set were arranged to alternate with the corresponding coils of theother set whereby a multiplied output was obtained in reponse to a flaw.It has been customary to mount all of said coils within a housing whichwas supported on a carriage at a constant distance above the railsurface. This construction, however, was found to be subject to pickingup irregularities in 'fiux due to surface defects such as burns causedby the slipping of locomotive wheels and which were not internaldefects. It was found that if each coil, could be so mounted that itfollowed the contour of the rail surface and could at all times maintainits parallelism with said surface, such surface defects did not affectthe detector means and therefore caused no confusion with real internaldefects. It has therefore been proposed that each coil be mountedindividually as shown in applicants Patent No. 1,960,968 granted May 29,1934, but this necessitated a complicated construction and resulted inerror because one coil of a balanced pair could move laterally withrespect to the other coil with a result that induced E. M. F., thusgiving an indication of flaw where none actually existed. I

It is the object of the present invention to provide a mounting for aplurality of sets of coils which will permit each coil of each set tomain- (tCl. 175-183) tain its axis at all times at a fixed distanceabove the rail surface by following the contour of the rail surface andat the same time prevent lateral movement of one coil of a balanced pairrelative to the other coil. y it Further objects and advantages of thisinven-'- tion will become apparent in the following detailed descriptionthereof.

In the accompanying drawing,

Fig. 1 is a side elevation of a portion of a Sperry 1o rail flawdetector car showing my invention applied thereto.

Fig. 2 is an enlarged side elevation of the detector mechanism and itsmounting.

Fig. 3 is a plan view of the detector mechanism 15 of Fig. 2, i

Referring to Fig. 1, there is shown a portion of a Sperry rail flawdetector car adapted to' travel along the rails to be tested. Current issupplied to the portion of the rail under test from a generator G withinthe car which supplies current to the rail R by means of sets of brushesH and i2. Said brushes l l and B2 are carried by a current brushcarriage i5, said carriage being supported from the car body by meanssuch as 25 cables l6 and springs, not shown, which normally maintain thecurrent brush carriage in raised or ineffective position. When it isdesired to lower said carriage into engagement with the rail,

fiuid pressure such as compressed air is supplied 30 to cylinders H todepress pistons l8 operating therein, said pistons being connected tothe current brush carriage so that said carriage is lowered against theaction of the retractile springs. The current brush carriage may be 35adapted to ride along the rail on means such as flanged wheels iii.

The electromagnetic field surrounding the rail is uniform as long asthere are no flaws. When flaws occur there is a distortion of theelectromagnetic field in the region of the flaw and such distortions aredesigned to be detected by induction means which maycomprise a pluralityof \pairs of opposed induction coils 20,20, each of said. pairs ofinduction 'coils being supported in a with respective widths of therailhead, one coacting mainly with the portion of the rail head near thegauge side and the other with the portion of the rail head near theoutside. The coils of each pair are balanced and oppositely wound, andthe coils of one pair alternate with the corresponding coils of theother pair. It will now be seen that as the car travels along the raileach pair of inductive coils 20, 20' will normally cut a constant numberof lines of force as long as the rail is free from defect, since theelectromagnetic force is undistorted. When a region of flaw isencountered, one'of the coils of each pairwill cut a different number oflines of force and there will be generated a differential E. M. F. whichafter being amplified may be caused to operate indicating means, such aspens operating on a chart, and rail marking means, such as a paint gun.The alternating arrangement of the coils provides a larger response to aflaw than could be obtained by either pair of coils separately by reasonof the fact that the impulses generated by the pairs of coils in thisarrangement reinforce each other.

The accuracy of the detector mechanism dep nds upon maintaining the axisof the coils at all times at a fixed distance above the rail surface.For this reason itis highly desirable that some provision be madewhereby the coils may follow the contour of the top surface of thelrailsince a burn or similar defect on the surface will 'tend to increase thedistance of the axis from the rail surface and thus cause the coils tocut a different number of lines of force than normally to induce an E.M. F. and give a false indication of flaw. To permit the coils to followthe contour of the rail surface without complicating the mechanismwhereby the housings 2| .and 2| are supported on the detector carriage22, I have provided for a mounting of each housing 2| and 2| on apivotal axis formed by bearings 30, 30' on the upper surface of thehousings 2| and 2|. Bell-cranks 32, 32' are pivotally -J'ournaled at 34,34' on the detector carriage 22,

maintain the housings 2 2| in depressed position' in engagement with therail, but permitting said housings to adjust themselves to surfaceirregularities. The housings 2|, 2| may ride upon the rail 'either onsleds 39, or upon rollers as shown in applicants Patent No. 1,960,968,granted May 29, 1934.

By the construction described above it will be seen that each housing2|, 2| is free to pivot about its axis 30, 30' and about the axes 34,34', so that each end of the housing may follow the contour of the railinto each hollow or elevated portion, as case may be, and thus maintainthe axis of the coila constant distance above the Portion of the railwhich it is testin irrespective of the movements of detector carriage22. At the same time, it is impossible for one 'coil of a pair to movelaterally relative to the other coil, which movement would generate animpulse like that of a flaw, by reason of the mounting of each balancedpair in a housing which is so mounted that both ends thereof areconstrained to move laterally tothe same degree. Stops 4| and 4| may befixed to the carriage 22 in the path of movement of the bell-crank tolimit the downarrangement of coils is made possible, whereby strongerimpulses are obtained at the flaws; and, second, each pair of balancedcoils is contained in its own housing and the housing so mounted that itis impossible for one coil of a pair to move laterally with respect tothe other coil.

In accordance with the provisions of the patent statutes, I have hereindescribed the principle and operation of my invention, together with the20 apparatus which I now consider to represent the best embodimentthereof, but I desire to have it understood that the apparatus shown isonly illustrative and that the invention can be carried out by otherequivalent means. Also, while it 25 is designed to use the variousfeatures and elements in the combination and relations described, someof these may be altered and others omitted without interfering with themore general results outlined, and the invention extends to such use. 30

Having described my invention, what I claim and desire to secure byLetters Patent is:

1. In a rail flaw detector car, flaw responsive means comprising aplurality of sets of inductive means, a housing for each set, each ofsaid hous- 35 ings having means, engaging the rail, a support for saidhousings, and means whereby each of said housings is pivotally mountedon said support for movement about an axis transverse to the rail; saidaxis being positioned intermediate the inductive means in each housing.

2. In a rail flaw detector car, flaw responsive means comprising aplurality of sets of inductive means, a housing for each set, each ofsaid housings having means engaging the rail, a support for saidhousings, and means whereby each of said housings is pivotally mountedon said support for vertical movement relative to said rail and saidsupport, and means whereby each of said housings is pivotally mountedfor rocking movement about an axis transverse to the rail.

3. In a rail flaw detector car, flaw responsive means comprising aplurality of sets of inductive means, a housing for each set, each ofsaid housings having means engaging the rail, 9. support for saidhousings, and means whereby each of said housings is pivotally mountedon said support about an axis transverse to the rail for verticalmovement relative to said rail and said sup port;and means whereby eachof said housings'oo is pivotally mounted for rocking movement about anaxis transverse to the rail.

4. In a rail flaw detector car, flaw responsive means comprising aplurality of sets of inductive means, a housing for each set, each ofsaid housings having means engaging the rail, a support for saidhousings, and means whereby each of said housings is pivotally mountedon said support about an axis transverse to the rail for verticalmovement relative to said rail and said support, and means whereby eachof said housings is pivotally mounted for-rocking movement about an axistransverse to the rail, said last-named axis being positioned betweenthe inductive means in each housing.

anaemia 5. In a rail flaw detector car, flaw responsive means comprisinga plurality of sets of inductive means, a housing for each set, each ofsaid housings having means engaging the rail, a support for saidhousings, and means whereby each of said housings is pivotally mountedon said support, said last-named means comprising a plurality of links,each link pivotally connected at one end to said support and pivotallyconnected at the other end to one of said housings.

6. In a rail flawdetector car, flaw responsive means comprising aplurality of sets of inductive means, a housing for each set, each ofsaid housings having means engaging the rail, a support for saidhousings, and means whereby each of said housings is pivotally mountedon said support, said last-pained means comprising a plurality of links,each link pivotally connected at one end to said support and pivotallyconnected at the other end to one of said housings, each of said pivotalconnections being about an axis transverse to the rail.

7. In a rail flaw detector car, flaw responsive means comprising aplurality of sets of inductive means, a housing for each set, each ofsaid housings having means engaging the rail, a support for saidhousings, means whereby eachof said housings is pivotally mounted onsaid support for vertical movement relative to said rail andsaidsupport,means whereby each of said housings is pivotally mounted for rockingmovement about an axis transverse to the rail, .and means for limitingthe movement of said housings relative to said support 8. In a rail flawdetector car, flaw responsive means comprising a plurality of sets ofinductive means, each set comprising a pair of balanced coils, saidcoils being arranged so that the-coils of one pair alternate with thecorresponding coils of another pair, a housing for each pair of coils,

, pair alternate with a support for said housings, and means wherebyeach of said housings is pivotally mounted on said support. 7

9. In a rail flaw detector car, flaw responsive means comprising aplurality of sets of inductive 5.

rail head, said coils being arranged so that the 10 coils of one pairalternate with the corresponding coils of another pair, a housing foreach pair of coils, a support for said ,housings, and means whereby eachof said housings is pivotally mounted on said support. 15 10. Ina railflaw detector car, flaw responsive means comprising a plurality of setsof inductive means, each set comprising a pair of balanced coils, onepair cooperating principally with the gauge side of the rail head andthe other pair 20 cooperating principally with the outside of the railhead, the portions of the ,rail head with which said pairs of coilscooperate overlapping, said coils being arranged so that the coils ofone the corresponding coils of 25 another pair, a housing for each pairof coils, the portions of the rail head withwhich said housingscooperate overlapping, a support for said housings, and means wherebyeach of said housings is pivotally mounted on said support. 30 11. In arail flaw detector car, flaw responsive means comprising a plurality ofsets of inductive means, eachset comprising a pair of balanced coils,said coils being arranged so. that the coils of one pair alternate withthe corresponding coils of another pair, a housing for each pair ofcoils, and a support for each of saidhousings including meansforconstraining said housings to vertical movement.

r HARCOURT C. DRAKE. 4

